Enantiomerically pure 1,3-thiazolidine-derived spiro-β-lactams were stereoselectively synthesised by means of a Staudinger ketene-imine reaction starting from optically active N-Boc-1,3-thiazolidine-2-carboxylic acid derivatives and imines. The reactions were stereoselective and afforded spiro-β-lactams with a relative trans-configuration. The absolute configuration of the new stereocentres was assigned on the basis of the well-accepted mechanism and confirmed by means of the X-ray crystal structure analysis. The spiro-β-lactams were transformed into enantiomerically pure chiral monocyclic β-lactams by opening the thiazolidine ring and recovering the chiral auxiliary.
Asymmetric synthesis of 1,3-thiazolidine-derived spiro-beta-lactams via a Staudinger reaction between chiral ketenes and imines / G. Cremonesi, P. Dalla Croce, F. Fontana, A. Forni, C. La Rosa. - In: TETRAHEDRON-ASYMMETRY. - ISSN 0957-4166. - 16:20(2005), pp. 3371-3379. [10.1016/j.tetasy.2005.08.054]
Asymmetric synthesis of 1,3-thiazolidine-derived spiro-beta-lactams via a Staudinger reaction between chiral ketenes and imines
G. CremonesiPrimo
;P. Dalla CroceSecondo
;F. Fontana;C. La RosaUltimo
2005
Abstract
Enantiomerically pure 1,3-thiazolidine-derived spiro-β-lactams were stereoselectively synthesised by means of a Staudinger ketene-imine reaction starting from optically active N-Boc-1,3-thiazolidine-2-carboxylic acid derivatives and imines. The reactions were stereoselective and afforded spiro-β-lactams with a relative trans-configuration. The absolute configuration of the new stereocentres was assigned on the basis of the well-accepted mechanism and confirmed by means of the X-ray crystal structure analysis. The spiro-β-lactams were transformed into enantiomerically pure chiral monocyclic β-lactams by opening the thiazolidine ring and recovering the chiral auxiliary.
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